Most long-distance refrigerated transport by truck is done via tractor-trailer trucks in which the tractor pulls a refrigerated semi-trailer, or “reefer”. Reefers are generally equipped with a mechanical refrigeration system powered by small displacement diesel engine. Commonly, the fuel for the engine is carried in a fuel tank attached to the bottom of the trailer, for example, using a bracket arrangement that holds the tank in a fixed position in close proximity to the trailer. A fuel level sensor is generally installed on the tank to monitor the level of fuel in the tank during normal reefer operation. A portion of the fuel sensor called a down tube is disposed within the tank and maintains contact with the fuel to detect the level of fuel in the tank. In the prior art, the down tube is rigid and extends from the top of the tank to near the bottom of the tank, and is thereby able to detect the level of fuel in the tank at essentially any level. To install the fuel sensor on the tank, the down tube is inserted into the fuel tank through a hole in the top of the tank. The down tube connects to a portion of the sensor comprising electronics that remains outside of the tank. The tank with the sensor installed is then attached to the trailer, oriented so that the hole and sensor electronics are located at the top of the attached tank.
In general, the distance between the bottom of the trailer and the top of the attached tank is much smaller than the depth of the tank. Hence, the length of the installed down tube is much greater than the clearance between the tank and the trailer. Accordingly, the sensor cannot be installed on the tank when the tank is attached to the trailer, because the clearance is not sufficient for the down tube to be inserted into the tank. Moreover, in order to replace a fuel sensor, the tank must be removed from the trailer. Most commonly the tank is emptied, detached from the trailer and rotated to provide the clearance required to remove the fuel sensor and install a replacement. After the new sensor is installed, the tank must be rotated back to its upright position, reattached to the trailer, and refilled with fuel. This is a time consuming and inconvenient operation, particularly if the tank contains a large amount of fuel.